Vinod K. Puri

Complications of vascular catheterization in the critically ill. A prospective study.

Invasive hemodynaniic procedures are increasingly used for monitoring critically ill and injured patients. The results of a prospective study on complications of 210 vascular catheterizations in 116 critically ill patients are reported. A total of 80 central venous (CV), 71 pulmonary artery (PA), and 59 arterial (A) catheterizations were performed during an interval of 6 months. Catheters were inserted by percutaneous techniques for all but seven of the procedures. CV catheters were associated with complications in 3.7%. However, complications were encountered in 10% of the PA catheterizations and 13.5% of systemic A catheterization. It appears that in a group of patients with observed hospital mortality of 36%, invasive monitoring is associated with a significant complication rate.

Catheter colonization and bacteremia with pulmonary and arterial catheters.

We prospectively studied the incidence of catheter-related sepsis in 51 critically ill patients who underwent 52 arterial and 37 pulmonary artery catheterizations over a period of 3 months. Daily cultures of blood and catheter insertion site were done and the catheters were cultured semiquantitatively at the time of removal. Catheter colonization defined as growth of 15 or more colonies was observed with 9 (10%) catheters and bacteremia with 4 (4.5%) catheters. The skin cultures were positive in 56% of the colonized catheters compared with 11% of sterile catheters (p < 0.01). The mean duration of catheterization of 3.8 days in colonized catheters was not different than 3.3 days in noncolonized catheters. Presence of concurrent infection and use of antibiotic did not change the rate of catheter colonization. Often, microorganisms other than those colonizing the catheter were recovered from blood. Femoral arterial catheterization appeared to be more often associated with colonization than radial catheters.It appears that the arterial and pulmonary artery catheter colonization occurs in about 10% of catheters and predisposes to catheter-related sepsis. Semiquantitative cultures of the catheter may aid in better documentation of catheter-induced sepsis.

Circulatory shock associated with purulent peritonitis.

The relative roles of bacterial infection, fluid loss and myocardial failure were investigated in 24 patients in whom circulatory shock appeared as a complication of purulent peritonitis. The 13 acute survivors, including 6 hospital survivors, had strikingly lower initial plasma volumes and total blood volumes than the 11 patients who died. Differences in blood volume were not explained by differences in previous treatment or in duration of peritonitis. Acute survivors promptly improved after fluid repletion, whereas the patients who died failed to respond to the infusion of equivalent volumes of fluid. In contrast to acute survivors, the fatal cases demonstrated disproportionate increases in both right- and left-sided filling pressure, increases in pulmonary vascular resistance and decreased right and left ventricular work capability. These observations in patients complement experimental studies in which biventricular cardiac failure was implicated in the fatal progression of septic shock.

Cardiac output changes and continuous mixed venous oxygen saturation measurement in the critically ill

For many years, the pulmonary artery catheter has been used to monitor cardiac filling pressures and to determine cardiac output in hemodynamically unstable patients. Recently, a new pulmonary artery catheter with fiberoptic capabilities, which provides continuous mixed venous O2 saturation (SvO2) measurements, has become available and has been found to be helpful in managing unstable patients. To determine the efficacy of this device in predicting early changes in cardiac output, we studied 46 patients catheterized with the opticath and 25 with the standard pulmonary artery catheter; we compared changes in the SvO2 with associated cardiac index changes. We found that small changes (5%) in SvO2 did not correlate well with changes in cardiac output, yet larger changes (10%) in SvO2 seemed to correlate better. More importantly, we found that only 50% of the SvO2 changes predicted anticipated changes in cardiac output. As can best be determined from the limitations of a nonrandomized study, the value of continuous SvO2 monitoring as an early predictor of cardiac output change remains questionable.

Cardiopulmonary resuscitation in hospitalized patients: continuing problems of decision-making.

Disturbingly low survival rates after CPR prompted us to carry out a series of studies. Of 272 patients receiving CPR at our 600-bed community hospital in 1984,102 (37.5%) patients survived initial resuscitation and 30 (11%) survived their hospitalization. Of the 102 initial survivors, only 15 patients had received full CPR including cardiac compression and/or defibrillation, endotracheal intubation, and cardiotonic drugs. These data were compared with those for 129 patients admitted to our critical care units in 1982 and 1983 in whom CPR was withheld. These patients had been designated “No CPR” primarily because of their poor response to therapy. There was an 11% survival rate for patients who had received CPR compared to a 16% survival rate for the “No CPR” group. These data suggest that criteria for administering CPR to hospitalized patients should be improved.

Hydroxyethyl starch for resuscitation of patients with hypovolemia and shock

The authors evaluated the effectiveness of 6% hydroxyl-ethyl starch (hetastarch) solution for treatment of hypovolemia in 46 critically ill patients. Thirty-two of the patients were studied retrospectively and in 14 patients, cardiopulmonary variables were prospectively measured. A total of 29 patients were in shock secondary to hypovolemia (13), sepsis (13), or myocardial infarction (3). Average hetastarch infusion volume was 829 and 842 ml, respectively, in prospectively and retrospectively studied patients, with maximum volumes of 2000–2500 ml infused over 48 h. Approximately 30% of 24 h fluid needs were supplied with colloids.Infusion of 500 ml of hetastarch in 14 prospective study patients was associated with increases in pulmonary artery wedge pressure (WP) from 9 ± 1.5 to 12 ± 2.1 mm Hg, cardiac index (CI) from 2.9 ± 0.2 to 3.5 ± 0.3 (p < 0.05) along with an increase in mean arterial pressure (MAP) from 87–99 mm Hg and reduction in arteriovenous O2 difference [C(a-v)o2] from 4.9 to 4.2 ml/dl. Intrapulmonary shunt (Qsp/Qt) was similar (20 vs. 21% as were alveolar-arterial O2 gradient [P(A-a)o2] (165 vs. 158 torr), whereas O2 consumption (Vo2) increased from 224 to 247 ml/min. Immediate survival was 90% in shock patients and 100% in nonshock patients, whereas hospital survival was 65.5% and 88%, respectively. The authors conclude that hetastarch is an effective fluid for resuscitation of hypovolemic patients. This synthetic colloid does not appear to adversely affect pulmonary function.

Resuscitation in hypovolemia and shock: a prospective study of hydroxyethyl starch and albumin.

In a prospective study comprising 50 patients, we evaluated the hemodynamic, pulmonary, renal and coagulation changes after resuscitation with 2 colloidal fluids, 6% hydroxyethyl starch (HES) and 5% albumin (ALB). Twenty-five patients studied in each group were well matched for age, clinical presentation, presence of shock and type of surgical proceures. A standard fluid challenge with 500 ml of either solution significantly (p<0.01) increased pulmonary artery wedge pressure (WP), mean arterial pressure (MAP) and left ventricular stroke work index (LVSWI) and decreased systemic vascular resistance index (SVRI). Increases in LVSWI of 43% to 68% over baseline in HES patients compared favorably to 15–22% increases in ALB patients.The cardiopulmonary variables at 12 and 24 h were comparable in both groups. Improvement in cardiac function was also reflected by better tissue perfusion as judged by reduction in arterial lactate from 2.9 to 1.5 mM/L (ALB) and 2.6 to 1.4 mM/L (HES). Increased O2 delivery and reduced O2 extraction without significant deterioration of Pao2 or alveolar-arterial O2 gradient were observed with stabilization of circulation. Clinical bleeding due to colloid resuscitation was not documented and renal function was not affected significantly by either fluid. It seems that HES may offer a cost-effective alternative to ALB for patients requiring colloid resuscitation.

Critical Care Scoring System--new concept based on hemodynamic data.

Based on the rationale that hemodynamic, oxygen transport, and perfusion derangements describe physiologically important abnormalities in critically ill patients, we devised a Critical Care Scoring System (CCSS). The database includes a retrospective analysis of 318 patients managed with pulmonary artery catheters during 1986 to 1988. For comparison, Acute Physiology and Chronic Health Evaluation (APACHE II) score was computed for these patients. CCSS includes a total of 17 variables with a weighted score of 71.The mortality rates for increases by 5 points were observed and were statistically significant (p < .0001). The same was not true for APACHE II. Although neither of the scores could predict ICU days, both reflected the number of life-threatening complications.Serial CCSS that was computed at 24 ± 4 h (CCSS-C) provided documentation for improvement in patient condition secondary to therapeutic interventions. Statistically improved mortality prediction was observed with CCSS-C. Since 70 (45.7%) of 153 patients died with an APACHE II score <14, it appears that this score is deficient in a specific group of patients, i.e., those requiring invasive monitoring. For patients with circulatory or respiratory failure, CCSS may offer a better tool to predict mortality and evaluate therapy.

Detection of right atrial mass by echocardiography in pulmonary thromboembolism.

An echodense mass in the right atrium was detected incidentally by two-dimensional echocardiography (ECHO) in a patient with clinical suggestions of cardiogenic shock. Autopsy revealed a cylindrical thrombus extending from the right atrium through a patent foramen ovale, and bilateral massive pulmonary thromboembolism (PTE). Pulmonary thromboembolism should be one of the differential diagnoses in patients with an echodense mass in the right heart.

Mathematical model to study fluid and protein transfer in pulmonary edema in man

We developed a mathematical model that integrates the various processes that affect fluid and protein transport in the lung. The model is based on experimental data and current concepts of fluid and protein transfer in the lung, with particular attention to experimental studies of lymph flow and protein content. The model is exercised with data obtained from 5 patients with fulminant pulmonary edema who are studied prospectively. Tracheobronchial fluid (TBF) was sampled sequentially during the course of edema. In addition, radioiodinated human serum albumin (RIHSA) was injected iv and its appearance was measured in TBF as well as in plasma (P). The oncotic pressure of P and TBF, together with the measured pulmonary vascular hydrostatic pressure, and the appearance of RIHSA in TBF were used to exercise the model. Water flux across the microvascular wall was calculated using the Starling equation, and the equation for protein transport utilized terms for convection and diffusion. Transport coefficients were estimated which produced the closest fit between the mathematically calculated and measured values for TBF protein concentration and the rate of RIHSA appearance in TBF for each patient.For patients with permeability edema, our mathematical model estimated that bulk flow coefficients, Kf for water flux and (1 – σ) for convective flow of protein increased while the estimate of the coefficient for protein diffusion ω was increased to a lesser extent. In hemodynamic edema, the model predicted Kf and ω to be somewhat elevated, but because the estimated σ was unchanged, there was no massive loss of protein from the vascular space. The measured values and the values calculated by the model for TBF/P protein ratio averaged 0.66 for hemodynamic edema, and 0.94 for permeability edema. The model predicted that a maximal increase in lymph flow, consistent with experimentally measured values, would substantially reduce extravascular volume in hemodynamic edema within 24 h, but would have little effect in permeability edema. One explanation for the observed greater concentration of tagged protein in the TBF than in P in 1 patient is provided by the model. The time after RIHSA injection when this crossover is predicted by the model averaged 20 h in hemodynamic edema, but only 4 h in permeability edema. The duration of this time interval may be a useful variable to distinguish the 2 types of edema.We recognize the shortcomings of a model based on disparate experimental data. However, we believe that the model provides a method to help improve our understanding of edemagenesis. The model gives the clinical investigator a prediction of what may follow the manipulation of one or more of the multiple variables that influence edemagenesis. As additional clinical and experimental knowledge of edemagenesis accumulates, the model can be refined.